Dear Fellow Boaters,
First of all, I have to mention that I did quite a research/reading in the forums regarding speed issues and made myself a bit smarter on wider trim tabs, longer drop fins, weight distribution, max rpm without load etc.
I hope to hear other creative ideas about this specific case
So, I have a '90 3288 with twin 150HP water cooled turbo Hino's. (Engine hour 4800)
There is some confusion, whether these are 135HP or 150HP because the manual mentions both, but the engine code is W04C-T.
Facts:
-Purchased the boat 4 months ago. At the sea-trial the boat did 15knots (nautical miles) at WOT. Bottom of the boat had some growth by that time.
-I did another sea trial 1 month after purchasing and we reached about 14knots at WOT. The bottom was already cleaned by the diver with a sponge.
-Max RPM at WOT was 2700 (according to tachs, but they are probably not that accurate). The play weird at times due to possible grounding issues.
-Previous owner had installed new propellers, he had no clue about the specs but I am sure they are a bit larger in diameter & pitch. I roughly measured 17.5 inch diameter during a haul-out
-Boat hauled-out, bottom cleaning and fresh antifouling paint. The old paint was not sanded-off, instead a primer coat was applied on top of the existing paint + 2 new coats.
-A new 180Ah battery (about 50kg) added to the aft battery bank, sits next to the transom between two engines.
-Oil change, filters change, cleaning of strainers, water separator check, brand new impellers
-We started our 500 miles trip to the destination. That was about 10 hours of uninterrupted run of engines. We found out that we could reach 10knots at WOT. So we travelled with 8-9 knots at 2400rpm.most of time.
-After 3 days and 250miles, both turbos gave up. Max RPM was about 2000 without turbos. Massive black smoke over 1800RPM.
-Stopped for maintenance: installed brand new injectors (all 8), port turbo revised, strbrd turbo brand new (old one was beyond repair), fuel pumps examined & changed all gaskets and seals. Strbrd cylinder head gasket changed. Manicoolers pipes chemically cleaned.
-The only thing we didn't is to measure the compression of the engine.
-There is not much additional weight on the boat, I placed some stuff into the locked under the fwd berth.
After all this max RPM without load (transmission neutral) is at 3400rpm; speed is barely 11knots at WOT at 2800RPM.
And we cannot get the boat to planing, which is very frustrating. We are basically getting burried into the water. Test was done with virtually empty water tank and 2/3 fuel on both tanks. Meanwhile I discovered that the behavior is independent of water/fuel level.
-and yes, 4 trim tabs are functional (brand is: Bennet)
Is there anything that I should be focusing now?
Thanks a lot!
First of all, I have to mention that I did quite a research/reading in the forums regarding speed issues and made myself a bit smarter on wider trim tabs, longer drop fins, weight distribution, max rpm without load etc.
I hope to hear other creative ideas about this specific case

So, I have a '90 3288 with twin 150HP water cooled turbo Hino's. (Engine hour 4800)
There is some confusion, whether these are 135HP or 150HP because the manual mentions both, but the engine code is W04C-T.
Facts:
-Purchased the boat 4 months ago. At the sea-trial the boat did 15knots (nautical miles) at WOT. Bottom of the boat had some growth by that time.
-I did another sea trial 1 month after purchasing and we reached about 14knots at WOT. The bottom was already cleaned by the diver with a sponge.
-Max RPM at WOT was 2700 (according to tachs, but they are probably not that accurate). The play weird at times due to possible grounding issues.
-Previous owner had installed new propellers, he had no clue about the specs but I am sure they are a bit larger in diameter & pitch. I roughly measured 17.5 inch diameter during a haul-out
-Boat hauled-out, bottom cleaning and fresh antifouling paint. The old paint was not sanded-off, instead a primer coat was applied on top of the existing paint + 2 new coats.
-A new 180Ah battery (about 50kg) added to the aft battery bank, sits next to the transom between two engines.
-Oil change, filters change, cleaning of strainers, water separator check, brand new impellers
-We started our 500 miles trip to the destination. That was about 10 hours of uninterrupted run of engines. We found out that we could reach 10knots at WOT. So we travelled with 8-9 knots at 2400rpm.most of time.
-After 3 days and 250miles, both turbos gave up. Max RPM was about 2000 without turbos. Massive black smoke over 1800RPM.
-Stopped for maintenance: installed brand new injectors (all 8), port turbo revised, strbrd turbo brand new (old one was beyond repair), fuel pumps examined & changed all gaskets and seals. Strbrd cylinder head gasket changed. Manicoolers pipes chemically cleaned.
-The only thing we didn't is to measure the compression of the engine.
-There is not much additional weight on the boat, I placed some stuff into the locked under the fwd berth.
After all this max RPM without load (transmission neutral) is at 3400rpm; speed is barely 11knots at WOT at 2800RPM.
And we cannot get the boat to planing, which is very frustrating. We are basically getting burried into the water. Test was done with virtually empty water tank and 2/3 fuel on both tanks. Meanwhile I discovered that the behavior is independent of water/fuel level.
-and yes, 4 trim tabs are functional (brand is: Bennet)
Is there anything that I should be focusing now?
Thanks a lot!
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